MDI Form

A Multiple Document Interface (MDI) programs can display multiple child windows inside them.

This is in contrast to single document interface (SDI) applications, which can manipulate only one document at a time. Visual Studio Environment is an example of Multiple Document Interface (MDI) and notepad is an example of an SDI application, opening a document closes any previously opened document. Any windows can become an MDI parent, if you set the IsMdiContainer property to True.

  IsMdiContainer = True

The following vb.net program shows a MDI form with two child forms. Create a new VB.Net project, then you will get a default form Form1 . Then add two mnore forms in the project (Form2 , Form 3) . Create a Menu on your form and call these two forms on menu click event. Click the following link to see how to create a Menu on your form How to Menu Control VB.Net.

Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        IsMdiContainer = True
    End Sub

    Private Sub MenuItem1ToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MenuItem1ToolStripMenuItem.Click
        Dim frm2 As New Form2
        frm2.Show()
        frm2.MdiParent = Me
    End Sub

    Private Sub MenuItem2ToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MenuItem2ToolStripMenuItem.Click
        Dim frm3 As New Form3
        frm3.Show()
        frm3.MdiParent = Me
    End Sub

End Class